DATA from bird ringers suggests that not all birds benefited from last spring’s mild weather and lack of human disturbance during the lockdown.
Figures from the British Trust for Ornithology (BTO) reveal how 24 species of songbird fared, with some suffering from a mismatch between breeding and food availability.
Lee Barber, the BTO’s demographic surveys officer, said: “In warm springs, caterpillars tend to hatch earlier and develop faster; birds also lay their eggs earlier, but not to the same extent, and so the availability of food peaks before the period when their young need it most, with fewer fledging as a result.
“The results from our ringers show that the average number of juvenile blue and great tits caught per adult was lower in 2020 than in any other year since the survey began almost 40 years ago.”
Positive trends were recorded among some songbirds returning to the UK after wintering in Europe.
“The abundance of chiffchaff and blackcap, two short-distance migrants that winter in southern Europe and North Africa, was the highest since monitoring began in 1983, and numbers of the declining willow warbler were also above average,” Barber added.
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